Bluetooth broadcast means that when other mobile phones turn on Bluetooth, they can scan the Bluetooth emitted by the bracelet.

Detailed explanation:

Bluetooth (Bluetooth?): It is a wireless technology standard that can realize short-distance data exchange between fixed devices, mobile devices and building personal area networks ( Using UHF radio waves in the ISM band of 2.4~2.485GHz). Bluetooth technology was originally created by telecommunications giant Ericsson in 1994 as an alternative to RS232 data lines. Bluetooth can connect multiple devices, overcoming the problem of data synchronization.

Today Bluetooth is managed by the Bluetooth Special Interest Group (SIG). The Bluetooth Technology Alliance has more than 25,000 member companies around the world, which are distributed in multiple fields such as telecommunications, computers, networks, and consumer electronics. The IEEE listed Bluetooth technology as IEEE 802.15.1, but this standard is no longer maintained. The Bluetooth SIG oversees the development of Bluetooth specifications, manages certification programs, and protects trademark rights. A manufacturer's device must comply with the Bluetooth SIG's standards before it can be marketed as a "Bluetooth device". Bluetooth technology has a proprietary network that is distributed to devices that comply with the standard.